1. Field of The Invention
The present invention relates to a plastic counterflow heat exchanger and more particularly to a counterflow heat exchanger that is inexpensive to manufacture and yet is efficient and effective.
2. Description Of The Related Art
Inexpensive plastic heat exchangers are very useful because of low manufacturing cost and because such heat exchangers can be custom molded to fit specific spaces, such as those in crowded, free-standing equipment cabinets commonly used to house telecommunications equipment. In such equipment cabinets, the fluid to be cooled is air from a sealed equipment compartment. The cooling fluid, typically, is ambient air. Hence, the fluids being handled are not usually corrosive, nor is high pressure involved.
Most plastic heat exchangers are of the cross flow type as exemplified by U.S. Pat. Nos. 4,997,031 and 4,858,685; and PCT applications SE82/00393 and GB98/03368. Cross flow heat exchangers are typically constructed of rectangular panels or sheets which are stacked together and which have small projections on one of their major surfaces to space one sheet from the next. The cooled fluid enters from one side of the rectangular stack and exits from an opposite side. In a like fashion the cooling fluid enters the stack from a side 90 degrees removed from the flow of the cooled fluid and exits through an opposite side. The fluid flows alternate between sheets, and seals are provided at the comers of the stack to separate the two flows. Such seals are generally adequate in cross flow heat exchangers.
An example of a plastic counterflow heat exchanger is UK patent application No. GB 2,158,569. However, ducting to and from the heat exchanger is not addressed in the application even though it is an important consideration in the design of such units. Further, seals for plastic counterflow heat exchangers are difficult to arrange. Hence, there is still a need for effective, efficient and low cost counterflow heat exchangers.
The present invention resolves some of the problems of the related art by providing a process for forming a plastic counterflow heat exchanger comprising the steps of molding a plurality of inner ducts, each duct having larger end portions and a smaller middle portion, stacking the inner ducts on their end portions whereby spaces exist around the middle portions, forming a seal around each stack of end portions, molding an outer duct, and positioning the outer duct about the stack of inner ducts.
It is an object of the present invention to provide a process for making a plastic counterflow heat exchanger which is simple, reliable and inexpensive. Another aim of the present invention is to provide a plastic counterflow heat exchanger having low tooling costs. Yet another aspect of the present invention is to provide a plastic counterflow heat exchanger process which allows inexpensive custom designs and dimensions for numerous different applications. Still another aspect of the present invention is to provide a plastic counterflow heat exchanger which is very efficient and highly effective.